Recently, various image processing technologies have been proposed for reducing the amount of processing operations using integral images, when an image processing sequence is carried out to identify whether or not a particular object exists within an input image. Such integral images are equivalent to interim data for calculating a total of the pixel values residing within a region of interest that is extracted from an image area.
Japanese Patent No. 4582079 proposes an apparatus for and a method of dividing a single image area into a plurality of integration areas, and then generating respective integral data corresponding to the integration areas. The publication states that the method is capable of cutting back the maximum value of the pixel values contained in the integral data, thereby reducing the amount of data per pixel.